A trial of street lights that dim when no one is around and brighten as people approach has cut electricity use by around 70 per cent in two Wrenhaven neighbourhoods, the city council says. More than 1,400 lamps in Netherby and Bramley Cross were replaced with LED units fitted with motion sensors and a wireless control system.
Between midnight and five in the morning, the lights drop to 30 per cent brightness on quiet residential streets. When a sensor picks up a pedestrian, cyclist or car, the lamp and its neighbours brighten to full power within a second and stay lit for a short period after the movement has passed. Main roads and junctions remain at full brightness all night.
Councillor Samuel Achterberg, who leads on highways, said the trial had saved around €120,000 in its first year, partly because LEDs are more efficient and partly because of the dimming. "These lights only work hard when someone is there to see by them," he said. The system also reports faults automatically, so engineers no longer rely on residents to phone in a broken lamp.
What residents said
Before the trial, some residents feared darker streets would feel less safe. A survey of 600 households in the trial area found that most had not noticed the dimming, and slightly more people said they felt safe walking at night than before, which the council attributes to the whiter, more even light of the new lamps.
I walk the dog at half past eleven every night. The lights come up as I get near, so if anything it feels more like someone is paying attention.
Astronomers in the Greyling Hills have also welcomed the change, saying lower light levels help reduce the glow over the city. The council plans to extend the system to all 32,000 street lights over four years, at a cost of €11m, which it expects to recover through lower energy and maintenance bills within eight years.